O que é Reality Check, superior predictive ability test?

For $K$ strategies with performance series $d_{k,t}$ in excess of a benchmark, the Reality Check (White, 2000) tests $H_0: \max_k\E[d_k] \le 0$ with the statistic $\max_k\sqrt n\,\bar d_k$, whose null distribution is estimated by the bootstrap of $\max_k\sqrt n(\bar d_k^* - \bar d_k)$. The superior predictive ability test (Hansen, 2005) studentises each $\bar d_k$ and recentres only the strategies that are not clearly worse than the benchmark, so that adding poor strategies to the search does not make the test more conservative.